1. Field of the Invention
The present invention relates to a process for the preparation of powdery detergent compositions having an improved spray-drying property, and the resulting powder detergent composition. More particularly, the invention relates to an improved powdery detergent composition which has been prepared by the spray-drying method and which comprises as the principal water-soluble organic surfactant component a polyoxyethylene alkyl ether, a polyoxyethylene alkylaryl ether, a sulfuric acid ester salt thereof or a mixture thereof.
2. Description of the Prior Art
A powdery detergent composition comprising as the main water-soluble organic surfactant component a polyoxyethylene alkyl ether, a polyoxyethylene alkylaryl ether, a sulfuric acid ester salt thereof or a mixture thereof, contains, in general, from 2 to 30% by weight of such surfactant and in addition, according to need, other conventional ingredients for laundry detergent compositions, including other water-soluble organic surfactants, inorganic or organic builders or chelating agents, a re-contamination-preventing agent, a diluent or extender, a fluorescent whitening agent, a foaming assistant, a perfume, an enzyme and a bleaching agent.
As the other water-soluble organic surfactant, there are generally employed anionic surfactants such as sodium alkylbenzenesulfonates, sodium alkyl sulfates and sodium .alpha.-olefinsulfonates. As the water-soluble organic or inorganic builders or chelating agents, there are used condensed phosphoric acid salts such as sodium tripolyphosphate, sodium metasilicate, sodium carbonate, citric acid and its salts, ethylenediamine tetraacetate and sodium nitrilotriacetate. As the re-contamination-preventing agent, there have heretofore been used carboxymethyl cellulose, polyethylene glycol, polyacrylic acid and its salts, and polyvinyl pyrrolidone.
These powdery detergent compositions are conventionally prepared by spraying into a hot gas stream an aqueous slurry containing the desired components at a solid content of about 60 to about 70% by weight. The powder detergent composition products obtained generally contain several weight percent of water.
However, a detergent composition comprising a polyoxyethylene alkyl ether, a polyoxyethylene alkylaryl ether, a sulfuric acid ester salt thereof or a mixture thereof, tends to generate a dense white smoke during the spray-drying step, and a serious problem of air pollution readily occurs.
Generation of this white smoke is due to combustion of the polyoxyethylene akyl ether, polyoxyethylene alkylaryl ether, or sulfuric acid ester salt thereof, or mixtures thereof, under the severe conditions present in a spray drier. As a procedure for overcoming this problem, there has been proposed a method in which the spray-drying is conducted in the presence of a specific phenolic compound or aromatic amine. This method, however, is not satisfactory because the dried detergent particles are discolored and this reduces drastically the commercial value of the detergent product.